By Michal Segal Rosenheimer, Research Scientist, NASA Ames Research Center

The Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) mounted on top of NASA’s C-130 research aircraft.Credit: NASA

The Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research, or 4STAR, is an airborne instrument that measures aerosols (small particles suspended in the atmosphere), gases (ozone for example), and a variety of cloud properties. Currently it is being deployed on the NASA C-130 aircraft on its quest to measure aerosol and cloud properties in the Arctic, helping to answer some of the most difficult questions of climate change: what is the link between sea ice changes, clouds and global warming?

How does it work?

The 4STAR instrument has three different modes. The first of these, and the instrument’s main mode, is Sun-Tracking. This is where the instrument tracks the sun’s location in the sky, staring at it to measure the light transmitted from the sun to the instrument as it travels through the atmosphere. If the atmosphere is clean, we would measure the sun’s intensity. But because the atmosphere contains aerosols, gases and cirrus clouds, which are high, thin clouds made of ice crystals, we measure the amount of light that makes it through instead of being scattered and absorbed by these components of the atmosphere. By comparing measured light through the atmosphere to what we would have seen with no atmosphere we can deduce the amount of aerosol and gases in the air.

A diagram showing 4STAR’s sun-tracking mode. The instrument locks on to the sun and measures the amount of light that makes it through clouds, gases and aerosols. Comparing this with what would be seen in clear air lets researchers calculate the amount of aerosols and gases in the atmosphere. Credit: NASA

Another operating mode, which will be used heavily during ARISE, would be the zenith (or upward) viewing mode. Here, we look upward to the sky and measure the diffused radiation that originated from the sun, but now is scattered due to aerosols and clouds. We use this measurement, along with assumptions on ground surface properties, cloud height, and the surrounding atmospheric composition to derive cloud properties such as optical depth (how much light gets through the cloud) and the size of water droplets in the cloud.

Diagram of how 4STAR measures cloud properties above the aircraft in zenith mode. In this mode, researchers can derive cloud water droplet size and how much light is transmitted through the cloud, or its optical depth.Credit: NASA

The last and most involved measurement mode we have is the Sky-Scanning mode. Here we measure the diffused sun radiation, that is light not coming directly from the sun, at different distinct angles from the sun (remember that we know where the sun is because we are tracking its location). This radiation is the result of scattered light from aerosols in the atmosphere. The amount of light at the different angles can tell us something about these aerosol particles, such as how well they absorb sunlight (and heat the earth), their shape (sphere or irregular), and their size.

Diagram showing 4STAR’s sky-scanning mode. The instrument scans the sky above the aircraft to measure how light is scattered by aerosol particles in the air.Credit: NASA

A new NASA airborne campaign known as ARISE, or the Arctic Radiation – IceBridge Sea and Ice Experiment, will take measurements intended to help researchers better understand the role that clouds play in Arctic warming as sea ice conditions change. From Sep. 3 to Oct. 3, researchers flying aboard NASA’s C-130 research aircraft will measure incoming and reflected sunlight, thermal infrared radiation, ice surface elevation and various cloud properties to gain a better understanding of changes to the Arctic climate.

NASA’s C-130 research aircraft sitting in the hangar at Wallops Flight Facility as it is being prepared for the ARISE field campaign. Credit: NASA / Christy Hansen

For the past few weeks, aircraft technicians and instrument experts have been preparing the C-130 for its upcoming trip to the Arctic. A large part of this process was installing and testing the scientific gear that the ARISE team will use to collect data on clouds and ice.

Ice Land, Vegetation and Ice Sensor (LVIS) – LVIS is a laser altimeter used to measure ice surface elevation. Data from this instrument can tell researchers about surface conditions below the plane.

Spectrometer for Sky-Scanning, Sun Tracking Atmospheric Research (4STAR) – 4STAR studies aerosol and cloud properties by measuring sunlight as it passes through the atmosphere.

Probes – The C-130 is also equipped with probes to measure properties like cloud water content and droplet size to better understand Arctic clouds.

Land, Vegetation and Ice Sensor (LVIS) instrument and control racks aboard the NASA C-130 research aircraft seen during instrument integration at Wallops Flight Facility in Virginia. LVIS is a laser altimeter that will be used to measure land and sea ice elevation during NASA’s ARISE campaign.Credit: NASA / David Rabine

Once the instruments are installed and tested on the ground, the ARISE team carried out a pair of check flights – one to make sure the C-130 is flying in peak condition and one to verify that the mission’s various instruments are working properly.

A view of NASA’s C-130 research aircraft seen from the T-34 chase plane during the ARISE engineering check flight on August 24, 2014.Credit: NASA / Dennis Rieke and Mark Russell

For the next few weeks, the ARISE team will fly out of Eielson Air Force Base, Alaska, to collect data on Arctic ice and clouds.

Members of the IceBridge team gather for a group photo on the last day of IceBridge’s 2014 summer science team meeting. Credit: UCI / Bernd Scheuchl

On June 24 and 25, 2014, the IceBridge science team met at the University of California Irvine. Twice a year, the IceBridge science team meets to share scientific presentations, discuss the mission’s performance and prepare for the next campaign.

A joint session of the land ice and sea ice teams. Credit: UCI / Bernd Scheuchl

Meetings typically begin with a joint session of the land ice and sea ice teams. These sessions focus on items of interest to the entire team such as updates from NASA Headquarters.

Later in the meeting the sea ice and land ice teams separate to discuss upcoming flight lines, opportunities for collaboration and the status of new and existing data products. The above photo shows a meeting of the sea ice team.

During each campaign IceBridge’s suite of instruments collects a vast amount of data on polar land and sea ice. These data have proven themselves useful with the research community using them in seasonal sea ice forecasts and computer simulations of ice sheets, and to build maps of the bedrock beneath the Greenland and Antarctic ice sheets. But getting IceBridge’s data into a place where researchers can use them is a big task.

After the end of a campaign researchers process instrument data and upload it to the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado. NSIDC then archives and publishes the datasets on the web where it is freely available to the public. IceBridge has a significant presence on the NSIDC website with more than 60 available datasets.

Preparing data is a time-intensive process and can take weeks or months to finish, but researchers are required to have their data in to NSIDC within six months of the campaign’s end.

The first step to making measurements public – after collecting them of course – is to back up the data. A good deal of this is done in the field. After each flight, instrument operators copy data onto media like external hard drives to be processed later. Following the campaign, instrument teams go through the data to process it and produce different data products suitable for posting.

Array of disks used to store instrument data during scientific flights. Credit: NASA / George Hale

These data products are categorized into different groups depending on how much processing they’ve undergone, following standards based on NASA’s Earth Science Reference Handbook, which was published in 2006. The level of processing for each dataset is noted by a letter L followed by a number (e.g., L0, L1B, L3) ranging from 0 (least processed) to 4 (most processed).

As an example, data from the Airborne Topographic Mapper go from distance between the surface and the instrument (L0), to ice elevation (L1B) and elevation, slope and roughness (L2), to surface elevation rate of change (L4).

Once processing is complete instrument teams send the data products to NSIDC, who stores the data on a public website. The NSIDC site contains separate pages for each instrument and data product and maintains a data portal where researchers can select individual IceBridge flights on an interactive map. Product pages contain a description of the dataset and links to documentation and software like file viewers.

A mileage sign just outside the terminal building at the Kangerlussuaq airport. Credit: NASA / Michael Starobin

A recent blog post talked about IceBridge’s home away from home, the Kangerlussuaq International Science Support Center. But what about the rest of the town of Kanger, as it is sometimes called? Here are a few photos from around this small town of about 500 people built around Greenland’s main transportation hub, the Kangerlussauq International Airport.

The small Greenland town of Kangerlussuaq. Credit: NASA / Michael Starobin

The airport and town of Kangerlussuaq can trace their roots back to military aviation, first as an airbase known as Bluie West-8 during World War II and later as a U.S. Air Force installation known as Sondrestrom airbase. The airport was turned over to civilian control in the early 1990s, though the 109th Airlift Wing of the New York Air National Guard maintains a presence there to support scientific activity in Greenland. In the above photo we can see pretty much the entire town, with the KISS facility and other similar buildings to the left. The large red building in the center of the photo is a hangar used by Air Greenland.

The majority of travelers heading to Greenland move through Kanger on their way to other parts of the country. Among these travelers are researchers who then head to research sites like Swiss Camp, Summit Station and various drilling sites all over the ice sheet. Many of the scientists working in Greenland will spend time at the Kangerlussuaq International Science Support, or KISS, center.

The Polar Bear Inn houses a convenience store and restaurant a short walk from KISS. Credit: NASA / Michael Starobin

Kanger is a small town, with fairly limited dining and shopping options. The airport cafeteria and main local grocery store are on the other side of town from KISS, unlike the Thai grill / pizzeria / convenience store known as the Polar Bear Inn seen in the above photo.

One of the bus stop shelters around town in Kanger. Credit: NASA / Michael Starobin

Despite being small there is a bus system in Kangerlussuaq, with several shelters like the one above throughout town. These shelters are unheated, but a welcome refuge from cold and wind.

A snowy day in Kangerlussuaq. Credit: NASA / Michael Starobin

Here we see what Kangerlussuaq looks like on a snowy and windy day. On average, Kangerlussuaq gets around five or six inches of total precipitation per year, though this spring seemed a little colder and stormier than during the last two IceBridge campaigns. Although Kanger might not get a lot of snow each year, the surroundings can get a little bland during the winter. Like many other places in the Arctic, locals counteract this by painting buildings in town different bold colors, which we can see in the above photo and the next one.

I thought I’d describe the facilities where the science team chooses to stay while here in Kangerlussuaq. One has the choice of staying in the airport hotel or in local lodging that is maintained for visiting scientists, the Kangerlussuaq International Science Support Center, or KISS.

KISS provides what can be called a dormitory for scientists, which is located in the former U.S. Air Force base. In the KISS dorm you get a room (generally two people to a room), and bed linens, common dorm bathrooms and washers/dryers down the hall. We do room cleaning ourselves, no services provided. There are two kitchens in the dorm, so we do a lot of cooking ourselves. Data processing is set up in one room downstairs.

A typical room in KISS. Credit: NASA / Jim Yungel

Groceries are sold in a small store near the airport, and because the store is generally only open when we are airborne, one IceBridge team person (who runs our ground GPS unit) ends up shopping for many of us when we fly. Most of us cook meals either teaming up in groups or as individuals after we fly and following our nightly science meeting and weather briefing at 6 p.m. There is a small “mini-store” with expanded hours near the KISS facility where a limited selection of items is available.

The large kitchen on the first floor of the KISS building. Credit: NASA / Jim Yungel

Besides cooking in the dorms, there are three restaurant choices here in this small airport village.

First is the airport cafeteria, which is being renovated this year and has limited service. No hot breakfasts, cold buffet only, a few selections of hamburgers, chicken, fish and the like for lunch. Dinner generally is re-heated lunch choices.

Second is the nearby Thai grill known as the Polar Bear Inn. Yes, this village in Greenland has a Thai restaurant. They serve pizza, hamburgers, hot dogs, fried chicken, and a Thai menu. The pizza is good, and I personally like the Thai soups. There is seating for about 20 folks in a fast food environment.

Last is the Roklubben, or Row Club, a restaurant by a lake about three miles from town. It’s been a formal restaurant since we began visiting here regularly in the 1990s, but after the air force left, several folks tried to run it on and off over the years. About five years ago, the present owner, Chef Kim took it over. He is strict. You must be on time, and have exactly the number of people in the reservations (no walk-ins.) The Roklubben has a limited menu for just a few days of the week, and about once a week, Kim puts on a Greenlandic Buffet like the one our group attended. It’s expensive (about $80US/person with a drink), but worth it for the experience and trying different Greenlandic food.

Usually we’re here in Kangerlussuaq for three or four weeks. We generally have one buffet meal at the Roklubben as a group. I try to cook several meals for every meal I eat at the Thai restaurant, either cooking for myself or with a small group. We also have our annual Easter ham dinner for the whole NASA team and many of the local KISS folks each year.

Most of the science team enjoys staying in the KISS facility. We end up being more social than if we live in hotels and eat every night in restaurants. There are group viewings of movies (played from computers), we traditionally work on jigsaw puzzles in the common rooms, go on hikes, and cook together frequently. Several folks are musicians and play guitars, and there are always entertaining discussions going on in the hallways and rooms.

I work as project manager with the Earth Science Project Office based at NASA Ames Research Center in Northern California. My group manages several Earth science research missions such as those studying hurricanes, atmospheric chemistry, and of course, the ice caps.

My job allows me to work with people of many backgrounds, and it is a constant learning process about the science, the technology, and what it takes to get these operations going, sustaining them, and completing them successfully.

These operations across the world are as challenging as they are rewarding. I have had the fortune of dealing with professional and dedicated people that have helped make my job easier and our missions successful.

Currently the 2014 Arctic campaign of Operation IceBridge is under way in Kangerlussuaq, Greenland, on a deployment that takes them to places as far north as Thule Air Base, Greenland, and as far west as Fairbanks, Alaska. After a lot of work, coordination, and pre-planning, and the constant and friendly support from the local resources available there, our operations there go very smoothly.

Mountainous sidewall of a glacier valley in eastern Greenland seen during the Apr. 5, 2014, IceBridge survey flight. Credit: NASA / George Hale

Operating out of a remote location for many weeks, with extremely cold temperatures and limited communications, and without the many comforts of home, can be a personal challenge to everyone on the Operation IceBridge team. These are challenges that the team has learned to endure over the years and they do so with professionalism, dedication and very positive attitudes. It is always easy to see and get a smile from them. It is a team that likes what they do and they do it well.

I have had the opportunity to go on many flights with IceBridge, and this year was one of them. It is something that never gets old and it gives me the opportunity to interact more closely with the team. I went on a flight that covered the glaciers of eastern Greenland. The flight itself was a smooth one, but the view was riveting. Flying over Greenland’s ice cap, so close to its glaciers, in between its mountains, and over its frozen rivers and oceans, is one of the experiences that I treasure the most.

On the morning of Apr. 15 the IceBridge team woke to blowing snow in Kangerlussuaq. The newly fallen snow made the ground a little slipperier than usual, forcing team members walking and driving to the airfield to take a little extra time. The blowing snow also limited visibility somewhat and led to a bit of ice buildup on the P-3, which presented the team with two problems.

NASA P-3 on the ramp at the Kangerlussuaq airport on a snowy morning. Credit: NASA / Jim YungelWindblown snow covers one of the P-3’s side windows. Credit: NASA / George Hale

First and foremost, ice buildup on a plane is unsafe. So when icy conditions prevail, airport ground crews spray aircraft exteriors with either an anti-icing substance to prevent ice buildup, or a deicing agent to remove what has built up. Although necessary in those cases, these agents present a problem for IceBridge researchers.

A deicing truck at the Kangerlussuaq airport ready to remove ice from the NASA P-3. Credit: NASA / Jim Yungel

Small windows on the bottom of the plane allow the lasers and cameras the Airborne Topographic Mapper and Digital Mapping System instruments use to collect data. These instruments point down through windows in the bottom of the P-3’s fuselage. The deicing agent left behind smudges up the windows, which can affect how these instruments perform.

The solution to this problem was pretty simple however. Once the airport ground crew was finished deicing the P-3, instrument team members ventured outside into the blowing snow with towels to wipe the remaining fluid off of the windows. Once the windows were clean it was time for everyone to strap into their seats for takeoff.

Members of the IceBridge team remove deicing agent from the P-3’s fuselage. Credit: NASA / George HaleP-3 aircraft technician James Schultz cleans one of the P-3’s bubble windows. Credit: NASA / George HalePolarTREC teacher Russell Hood and DMS engineer Caitlin Barnes discuss the finer points of cleaning the P-3. Credit: NASA / George Hale

During the week of Apr. 7 – 11, IceBridge was visited by a television production crew from the Al Jazeera America program TechKnow. During this week, the crew flew on an IceBridge survey flight and interviewed several members of the team for an upcoming episode of the show, tentatively scheduled for release in May.

“They were very easy to work with and made noticeable efforts keeping a low profile and getting their job done without impacting our daily work too much,” said Michael Studinger, IceBridge project scientist. “Their passion and dedication made them a natural fit for the IceBridge teams.”

TechKnow is a program focusing on the latest in science and technology and the people behind the science. For more about TechKnow visit:

The glaciers that flow out of the Greenland Ice Sheet move tons of ice out of the ice sheet each year. Many of these rivers of ice meet the ocean where relatively warm currents weaken the glacier’s terminus, causing icebergs to break off in a process known as calving. This forms a cliff-like feature called a calving front, where icebergs break off and fall into the sea.

The calving front of Jakobshavn Glacier and calved icebergs as it appeared in April 2012. Credit: NASA / Jefferson Beck

The presence of these currents is part of the reason why ocean-terminating glaciers are so dynamic. In contrast, land-terminating glaciers move more slowly and lose mass through melting on the surface rather than calving.

On a recent IceBridge flight, instruments aboard the P-3 captured views of two very different glaciers in east Greenland, the De Geer and Wahlenberg glaciers. The images below show the difference between a dynamic, ocean-terminating glacier (De Geer) and a land-terminating glacier that is essentially dormant (Wahlenberg).

Above is an image mosaic from the Digital Mapping System aboard the NASA P-3 showing the terminus of the De Geer Glacier in east Greenland. The heavily crevassed end of the glacier is to the left of the image and large icebergs are to the right. Credit: NASA / DMS / Eric Fraim

This image, is a plot showing data on De Geer Glacier from the Airborne Topographic Mapper instrument, a laser altimeter that measures ice surface elevation. Here we see the differences in elevation between before and after the calving front and in crevasses on the surface.

In contrast, this ATM plot of the land-terminating WahlenbergGlacier shows a smoother surface and more gradual change in elevation along its end.